Use FooterPreference in xml explicitly

Removed the FooterPreferenceMixin from the AutoBrightness page.

Fixes: 138916403
Test: manual test

Change-Id: I131d5cede156e2dae890342d5b456f347b025e27

res/xml/auto_brightness_detail.xml

@@ -39,4 +39,10 @@
         settings:userRestriction="no_config_brightness"
         settings:allowDividerAbove="true" />
 
+    <com.android.settingslib.widget.FooterPreference
+        android:key="auto_brightness_footer"
+        android:title="@string/auto_brightness_description"
+        android:selectable="false"
+        settings:searchable="false" />
+
 </PreferenceScreen>

src/com/android/settings/display/AutoBrightnessSettings.java

@@ -37,8 +37,6 @@ public class AutoBrightnessSettings extends DashboardFragment {
     @Override
     public void onCreate(Bundle icicle) {
         super.onCreate(icicle);
-        mFooterPreferenceMixin.createFooterPreference()
-                .setTitle(R.string.auto_brightness_description);
     }
 
     @Override